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B Cabrera

Publications and source records attributed to B Cabrera.

At least 19 recordsLinked to original sources
PubMed1993

A morphological study of the principal and accessory abducens nuclei in the caspian terrapin (Mauremys caspica).

The location of principal and accessory motoneurons and principal interneurons of the nucleus abducens was determined in the caspian terrapin (Mauremys caspica) by means of horseradish peroxidase histochemical tracing. Enzyme injections were made into the ipsilateral lateral rectus and retractor bulbi muscles and into the contralateral oculomotor nucleus. Labeled principal abducens motoneurons formed a cluster of cells in the rhombencephalon, under the IVth ventricle and adjacent to the medial longitudinal fascicle. The accessory abducens motoneurons were located more deeply in the rhombencephalon and more ventrolaterally than the principal motoneurons forming a compact aggregation of neurons. The principal interneurons of abducens nucleus were arranged as a cluster of cells under the floor of the IVth ventricle and more lateral than the principal motoneurons, with no intermingling.

Abducens Nerve↗
PubMed1992

Afferents to the oculomotor nucleus in the goldfish (Carassius auratus) as revealed by retrograde labeling with horseradish peroxidase.

The goal of this work was to compare the distribution and morphology of neurons projecting to the oculomotor nucleus in goldfish with those previously described in other vertebrate groups. Afferent neurons were revealed by retrograde labeling with horseradish peroxidase. The tracer was electrophoretically injected into the oculomotor nucleus. The location of the injection site was determined by the antidromic field potential elicited in the oculomotor nucleus by electrical stimulation of the oculomotor nerve. Labeled axons whose trajectories could be reconstructed were restricted to the medial longitudinal fasciculus. In order of quantitative importance, the afferent areas to the oculomotor nucleus were: (1) the ipsilateral anterior nucleus and the contralateral tangential and descending nuclei of the octaval column. Furthermore, a few labeled cells were found dorsomedially to the caudal pole of the unlabeled anterior octaval nucleus; (2) the contralateral abducens nucleus. The labeled internuclear neurons were arranged in two groups within and 500 microns behind the caudal subdivision of the abducens nucleus; (3) a few labeled cells were observed in the rhombencephalic reticular formation near the abducens nucleus, most of which were contralateral to the injection site. Specifically, stained cells were found in the caudal pole of the superior reticular nucleus, throughout the medial reticular nucleus and in the rostral area of the inferior reticular nucleus; (4) eurydendroid cells of the cerebellum, located close to the contralateral eminentia granularis pars lateralis, were also labeled; and (5) a small and primarily ipsilateral group of labeled cells was located at the mesencephalic nucleus of the medial longitudinal fasciculus. The similarity in the structures projecting to the oculomotor nucleus in goldfish to those in other vertebrates suggests that the neural network involved in the oculomotor system is quite conservative throughout phylogeny. Nevertheless, in goldfish these projections appeared with some specific peculiarities, such as the cerebellar and mesencephalic afferents to the oculomotor nucleus.

Afferent Pathways↗
PubMed1992

A morphological study of abducens nucleus motoneurons and internuclear neurons in the goldfish (Carassius auratus).

The location and distribution of abducens (ABD) nucleus motoneurons (Mn) and internuclear neurons (Int) were determined in the goldfish (Carassius auratus) by means of horseradish peroxidase and fluorochrome retrograde labeling. ABD Mn were labeled following tracer injection into the ipsilateral lateral rectus muscle. These Mn were arranged in two ventrolateral clusters along the rostro-caudal axis of the posterior brainstem. Both groups of neurons showed a similar number of cells, and their axons ran ventrally to their respective nerve roots. ABD Int were labeled following the injection of the tracer into the contralateral oculomotor nucleus. They also formed two distinct groups in the rostro-caudal axis. The rostral group of Int formed a dorso-lateral cap around the caudal motoneuronal pool, with little if any intermingling. The caudal group of Int was located at the same position in the dorso-ventral and medio-lateral axis as the rostral group, but 500 microns behind it. Both groups of ABD Int had a similar number of neurons. Int axons ascended dorso-medially, then crossed the midline through the internal arcuate fibers, and entered the contralateral medial longitudinal fasciculus. The soma diameters of both ABD Mn and Int were not significantly different. The relative location of both types of neurons is discussed.

Animals↗
PubMed1989

Cooper-pair mass.

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Journal Article↗
PubMed1989

Cytoarchitectonic organisation of the abducens nucleus in the pigeon (Columbia livia).

The distribution of abducens nucleus motoneurons and internuclear neurons was determined in the pigeon (Columbia livia) by injecting horseradish peroxidase or fluorochromes into the ipsilateral lateral rectus muscle and/or in the contralateral oculomotor nucleus. A small degree of intermingling of motoneurons and internuclear neurons in the caudal two thirds of the nucleus and an almost complete segregation of both types of neurons in the rostral third was observed. Both labelled populations, motoneurons and internuclear neurons, were more numerous at the central part of the abducens nucleus. Motoneurons were preferentially located nearer the medial longitudinal fasciculus and less numerous at the rostral end of the nucleus. Internuclear neurons were preferentially located further from the medial longitudinal fasciculus and were less abundant at the caudal end of the nucleus. The evolutionary trend of the relative location of both types of neurons is discussed in relation to the degree of conjugate eye movements.

Abducens Nerve↗
PubMed1988

Location of motoneurons and internuclear neurons within the rat abducens nucleus by means of horseradish peroxidase and fluorescent double labeling.

The distribution of abducens motoneurons and internuclear neurons was determined in the rat by injections of horseradish peroxidase or fluorochromes into the ipsilateral lateral rectus muscle and the contralateral oculomotor nucleus either separately or simultaneously. The labeled somata of abducens internuclear neurons were intermingled with the labeled motoneurons at the medial third of the nucleus, but they were more segregated at the rostral third, where the labeled interneurons were more numerous. Internuclear neurons were preferentially located around and ventral to the central part of the facial genu, while motoneurons were located more dorsomedially, closer to the midline than in other species of mammals. The evolutionary trend of the location of both populations of neurons is also discussed.

Abducens Nerve↗